Naturally occurring clays such as dioctahedral smectites are composed of semicrystalline aluminosilicate layers (lamellae) held together by Van der Waals and electrostatic forces. Anionic charges on the siliceous layers are neutralized by cations in the interlamellar spaces. These cations are usually sodium, calcium, or potassium. When these cations are large oligomers of inorganic cations such as Fe.sup.+3, Cr.sup.+3 or when they are metal hydroxy polymer cations such as [Al.sub.13 O.sub.4 (OH).sub.24 (H.sub.2 O).sub.12 ].sup.7+ or [Zr(OH).sub.2. 4H.sub.2 O].sub.4.sup.8+, they act as pillars, propping the clay layers apart to afford a pillared layered clay. Upon heating, these oligomers or polymers are converted to the metal oxide, thus preventing the collapse of the clay layers and pillaring the clay.
These smectite clays are known to catalyze reactions such as alkylation, cracking, ester formation, dimerization, oligomerization, etc. However, because the naturally occurring clays have a large variation in impurity content, industrial demand for the natural smectites has been very limited. Therefore, attempts have been made to synthesize some of these smectite clays. For example, European Patent Application 163560 discloses a method of preparing a beidellite clay (one of the smectite clays). The process involves taking a mixture containing aluminum nitrate, tetraethylorthosilicate (TEOS), sodium carbonate and sodium hydroxide, drying the mixture and then calcining to give aluminum oxide, silicon oxide, and sodium oxide, adding to that hydroxide anions and heating the resultant slurry to a temperature of about 340.degree. C. for 14 days.
The prior art also shows that synthetic micas can be prepared where the gallium is substituted for aluminum and germanium is substituted for silicon. For example, R. M. Barrer and L. W. R. Dicks in J. Chem. Soc.(A) (1966), 1379-1385, have reported the synthesis of micas in which the potassium counter ion is substituted by an ammonium counter ion, gallium is substituted for aluminum and germanium is substituted for silicon. Micas differ from dioctahedral smectite layered clays in that micas are not swellable due to the very high layer charge. Normally the mica charge is greater than 2 per formula unit while the charge on smectites varies from 0.4 to 1.6 per formula unit. The high charge found on micas leads to different chemistry than that for smectite clays.
Applicant has prepared a dioctahedral smectite clay in which the aluminum has been substituted by gallium and/or the silicon has been substituted by germanium. The clay composition is represented by the empirical formula EQU A.sub.x [M.sub.4 ](M'.sub.8-x M.sub.x)(O.sub.20)(OH).sub.4
where A is a templating agent, M is aluminum or gallium, M' is silicon or germanium, except that when M is aluminum, M' is not silicon and x is the moles of A and varies from about 0.1 to about 2.0.
These novel smectite clays can be produced by first forming a reaction mixture which contains reactive sources of the desired metals, a templating agent and water, and then reacting the reaction mixture at a pH of about 8.5 to about 14, a temperature of about 150 to about 210.degree. C. for a time of about 1 to about 20 days.